JP4418553B2 - Polyacetal resin composition - Google Patents

Description

【０１２０】
【表２】

【０１２１】
表より明らかなように、比較例に比べて、実施例の樹脂組成物は、コアシェルポリマーと抑制剤との組み合わせにより、耐衝撃性を高いレベルに維持しつつ、ホルムアルデヒドの発生を著しく抑制できる。[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a polyacetal resin composition having a significantly reduced formaldehyde generation amount and excellent impact resistance, and a polyacetal resin molded product molded from the resin composition.
[0002]
[Prior art]
Polyacetal resin has excellent mechanical properties, fatigue resistance, friction and wear resistance, chemical resistance and moldability, so it can be used for automobile parts, electrical / electronic equipment parts, other precision machine parts, building materials / piping members, Widely used in fields such as daily life, cosmetic parts, and medical parts. However, with the expansion and diversification of applications, the demand for quality has been increasing.
[0003]
The properties required for polyacetal resin are that mechanical strength does not decrease during processing such as extrusion or molding, that there is no deposit on the mold (mold deposit), and long-term heating conditions (heat aging). For example, the mechanical properties do not deteriorate, and molding defects such as silver streaks and voids do not occur. One important factor in these phenomena is the degradation of the polymer upon heating. In particular, polyacetal resins are essentially easily decomposed under acidic and alkaline conditions in a heated oxidizing atmosphere due to their chemical structure. Therefore, an essential problem of the polyacetal resin is that it has high thermal stability and suppresses generation of formaldehyde from the molding process or the molded product. Formaldehyde is chemically active and becomes formic acid by oxidation, which adversely affects heat resistance. When used in parts of electrical and electronic equipment, metal contact parts corrode or discolor due to adhesion of organic compounds, resulting in poor contact. Produce. Furthermore, formaldehyde itself pollutes the working environment in the parts assembly process and the living environment around the use of the final product.
[0004]
In order to stabilize chemically active terminals, homopolymers are esterified by polymerizing the polymer terminals by acetylation, etc., and copolymers are formed by adjacent carbon bonds such as trioxane, cyclic ether and cyclic formal during polymerization. A method is known in which an unstable terminal portion is decomposed and removed to form an inactive stable terminal after copolymerization with a monomer having the monomer. However, cracking also occurs in the main chain portion of the polymer during heating, and the prevention cannot be dealt with only by the above treatment, and practically it is essential to add an antioxidant and other stabilizers. .
[0005]
However, even if these stabilizers are blended, it is difficult to completely suppress the decomposition of the polyacetal resin. In practice, during the extrusion for preparing the composition and the melt processing in the molding process, an extruder or Under the action of heat and oxygen in the cylinder of the molding machine, formaldehyde is generated from the end of the main chain which is not sufficiently stabilized and is not sufficiently stabilized, deteriorating the working environment during extrusion molding. In addition, if molding is performed for a long time, fine powder and tar-like materials adhere to the mold (mold deposit), which is one of the greatest factors that reduce the work efficiency and the surface condition of the molded product. Yes. Furthermore, degradation of the polymer causes a decrease in mechanical strength and a color change of the resin. From such a point, with respect to the polyacetal resin, a great effort has been continued in search of a more effective stabilization formulation.
[0006]
As antioxidants added to polyacetal resins, sterically hindered phenol compounds (hindered phenols) and sterically hindered amine compounds (hindered amines) are known, and other stabilizers include melamine derivatives and amidine compounds. Alkali metal hydroxides, alkaline earth metal hydroxides, organic or inorganic acid salts are used. Usually, the antioxidant is used in combination with other stabilizers.
[0007]
In JP-A-6-136234, a polyacetal resin is added with an antioxidant, a weather resistance (light) stabilizer, and a melamine-formaldehyde polycondensate as another stabilizer, thereby improving weather resistance (light) resistance, heat It has been proposed to improve stability and moldability.
[0008]
However, even if such an additive is used, it is difficult to impart high stability to the polyacetal resin.
[0009]
Furthermore, it has been proposed to add a thermoplastic polyurethane to a polyacetal resin in order to impart characteristics required for molded parts such as automobile parts, for example, a high impact resistance in a wide temperature range (Japanese Patent Laid-Open No. 59). -145243, JP-A 61-19652). However, since the adhesiveness between the polyacetal resin and the polyurethane is not sufficient, the elongation of the welded portion of the molded product is reduced, or peeling occurs on the surface of the molded product, which impairs the appearance of the molded product.
[0010]
JP-A-7-268180 discloses a polyoxymethylene composition comprising a polyacetal resin, a core-shell polymer, an antioxidant, and a melamine-formaldehyde condensate that is insoluble in hot water and soluble in dimethyl sulfoxide. Things are disclosed. However, even with this resin composition, it is difficult to effectively and significantly suppress the generation of formaldehyde. Therefore, it is difficult to improve the stability (particularly thermal stability) of the polyacetal resin while maintaining the impact resistance at a high level.
[0011]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a resin composition capable of imparting high impact resistance and thermal stability (particularly, melt stability during molding) to a polyacetal resin, a method for producing the same, and a molded product.
[0012]
Another object of the present invention is to provide a polyacetal resin composition that can remarkably suppress the formation of formaldehyde with a small amount of addition and improve the working environment, a method for producing the same, and a molded article.
[0013]
Still another object of the present invention is to suppress the formation of formaldehyde even under harsh conditions, and to prevent the decomposition product from adhering to the mold, the leaching of the decomposition product from the molded product, and the thermal deterioration of the molded product. An object of the present invention is to provide a polyacetal resin composition that can be suppressed and that can improve the impact resistance of moldability, a method for producing the same, and a molded product.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the present inventors have intensively studied the improvement of stability and impact resistance of polyacetal resin, and as a result, when the core-shell polymer and urea or a derivative thereof or an amidine derivative are combined, a high level is obtained. It has been found that the polyacetal resin can be stabilized in a wide temperature range while maintaining the impact resistance, and the present invention has been completed.
[0015]
  That is, the polyacetal resin composition of the present invention comprises at least one inhibitor (formaldehyde) selected from polyacetal resin, a core-shell polymer having a soft polymer core and a hard polymer shell, and urea or a derivative thereof and an amidine derivative. Inhibitors for the production ofThe inhibitor is at least one selected from cyclic monoureido, cyclic diureido, and metal salts thereof.
[0016]
The core-shell polymer includes a core-shell polymer that is substantially free of free anions (for example, a core-shell polymer that is emulsion-polymerized in the presence of a nonionic surfactant), and the core-shell polymer includes a higher saturated fatty acid amide ( For example, it may contain a saturated fatty acid bisamide).
[0017]
TreeThe additive contained in the fat is, for example, about 1 to 100 parts by weight of the core-shell polymer and about 0.01 to 10 parts by weight of the inhibitor with respect to 100 parts by weight of the polyacetal resin.
[0018]
Furthermore, the present invention includes a molded article composed of the polyacetal resin composition.
[0019]
In the present specification, “urea derivative” is used to mean an N-substituted urea, a urea condensate, an acyclic or cyclic ureido derivative, a cyclic ureido metal salt, and the like. In addition, “amidine derivative” means RC (NH₂) = NH (R is a substituent having a substituent such as an alkyl group), and is used to mean a non-cyclic amidine and a non-melamine cyclic amidine. A nitrogen-containing compound other than the “inhibitor” is simply referred to as “nitrogen-containing compound”.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
The resin composition of the present invention is composed of a polyacetal resin, a core-shell polymer, and at least one formaldehyde inhibitor selected from urea or a derivative thereof and an amidine derivative.
[0021]
[Polyacetal resin]
The polyacetal resin is an oxymethylene group (—CH₂O-) as a main structural unit, a polyacetal homopolymer (for example, product name “Dellin” manufactured by Asahi Kasei Co., Ltd., product name “Tenac 4010”, etc., manufactured by DuPont, USA), oxymethylene group In addition, polyacetal copolymers containing other comonomer units (for example, trade name “Duracon” manufactured by Polyplastics Co., Ltd.) are included. In the copolymer, the comonomer unit includes an oxyalkylene unit (for example, an oxyethylene group (—CH 2) having about 2 to 6 carbon atoms (preferably about 2 to 4 carbon atoms).₂CH₂O-), an oxypropylene group, an oxytetramethylene group, and the like. The content of the comonomer unit is a small amount, for example, 0.01 to 20 mol%, preferably 0.03 to 10 mol% (for example, 0.05 to 5 mol%), more preferably, based on the whole polyacetal resin. It can select from the range of about 0.1-5 mol%.
[0022]
The polyacetal copolymer may be a copolymer composed of two components, a terpolymer composed of three components, or the like. The polyacetal copolymer may be a random copolymer, a block copolymer, a graft copolymer, or the like. Moreover, the polyacetal resin may have a branched structure as well as a linear structure, and may have a crosslinked structure. Furthermore, the terminal of the polyacetal resin may be stabilized by esterification with a carboxylic acid such as acetic acid or propionic acid or an anhydride thereof. The polymerization degree, branching degree, and crosslinking degree of the polyacetal are not particularly limited as long as it can be melt-molded.
[0023]
Examples of the polyacetal resin include aldehydes such as formaldehyde, paraformaldehyde, and acetaldehyde, cyclic ethers such as trioxane, ethylene oxide, propylene oxide, 1,3-dioxolane, diethylene glycol formal, and 1,4-butanediol formal, and cyclic formal. It can be produced by polymerization.
[0024]
The feature of the present invention is that by adding a combination of a core-shell polymer and an inhibitor, the impact resistance of the polyacetal resin is greatly improved, the thermal stability and the processing stability are improved, and the generation of formaldehyde is remarkably suppressed. There is in point to do. When the inhibitor is used, a stabilizing effect far surpassing that of conventional stabilizers is exhibited, and a polyacetal resin composition excellent in thermal stability and processability is obtained.
[0025]
[Core shell polymer]
The core-shell polymer is a polymer with a soft polymer (rubber-like polymer, rubber elastic body) or soft polymer phase core, and a hard polymer (glass-like polymer) shell in the outermost layer. Monomer, surfactant, polymerization It can be prepared by a conventional method using an initiator and water. Commercially available products can also be used as the core-shell polymer. Examples of commercially available products include trade names “Acryloid KM330” and “KM653” manufactured by Rohm and Haas, “Paraloid KCA-102” manufactured by Kureha Chemical Co., Ltd. ”And“ KCA-301 ”,“ Staphyroid PO-0270 ”,“ PO-0143 ”and“ PO-0135 ”manufactured by Takeda Pharmaceutical Co., Ltd.,“ Kane Ace FM ”manufactured by Kaneka Chemical Co., Ltd., Mitsubishi Rayon Examples thereof include “Metablene C-102”, “E-901”, “W-800”, “S-2001”, and the like.
[0026]
The core-shell polymer is usually obtained by a seed emulsion polymerization method, for example, a continuous multi-stage emulsion polymerization method in which the polymer produced in the preceding stage is sequentially coated with the polymer in the subsequent stage. An intermediate phase described later may be formed between the core phase and the shell phase of the core-shell polymer.
[0027]
Regarding the production of the core-shell polymer by such seed emulsion polymerization method, JP-A-3-14856, JP-A-5-271361, JP-A-9-95589, JP-A-9-310005 and the like can be referred to. .
[0028]
In the multi-stage emulsion polymerization, the first-stage polymerization is a reaction that forms a soft or rubber-like polymer, and the monomers that constitute the soft or rubber-like polymer include various polymerizable monomers that form a rubber elastic body, for example, A polymerizable monomer that forms a rubber elastic body having a glass transition temperature of −30 ° C. or lower (for example, about −40 ° C. to −100 ° C.) can be used, and a conjugated diene, an alkyl acrylate having 2 to 8 carbon atoms, or a mixture thereof. Etc. Examples of the conjugated diene include butadiene, isoprene, chloroprene and the like, and butadiene is particularly preferable. Examples of the alkyl acrylate having 2 to 8 carbon atoms in the alkyl group include ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, cyclohexyl acrylate, and 2-ethylhexyl acrylate, and ethyl acrylate and butyl acrylate are particularly preferably used. .
[0029]
In the first stage polymerization, monomers copolymerizable with conjugated dienes and alkyl acrylates, for example, aromatic vinyl such as styrene, vinyl toluene, α-methyl styrene, aromatic vinylidene, acrylonitrile, methacrylonitrile, etc. Alkyl methacrylates such as vinyl cyanide, vinylidene cyanide, methyl methacrylate, ethyl methacrylate, and butyl methacrylate may be copolymerized.
[0030]
In the first-stage polymerization for forming the core, when the monomer does not contain a conjugated diene, or when it contains a conjugated diene but not more than 20% by weight of the total amount of monomers, the crosslinking monomer and grafting By using a small amount of monomer, high impact resistance can be achieved.
[0031]
Examples of the crosslinkable monomer include aromatic divinyl monomers such as divinylbenzene, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, neo Examples include alkane polyol poly (meth) acrylates such as pentyl glycol di (meth) acrylate, oligoethylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, and trimethylolpropane tri (meth) acrylate. These crosslinkable monomers can be used alone or in admixture of two or more. Preferred crosslinkable monomers include butylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, and the like. Examples of the grafting monomer include unsaturated carboxylic acid allyl esters such as allyl (meth) acrylate, diallyl malate, diallyl fumarate, diallyl itaconate, and allyl methacrylate is preferably used. Such a crosslinkable monomer and a grafting monomer are used in a range of, for example, about 0 to 5% by weight, preferably about 0.1 to 2% by weight, based on the total amount of monomers constituting the core.
[0032]
The outermost shell is formed of a hard or glassy polymer, and the glass transition temperature of the glassy polymer is, for example, 40 ° C. or higher (eg, about 50 to 120 ° C.), preferably 60 ° C. or higher (eg, 70 to About 120 ° C.). As the monomer constituting the glassy polymer, a hard monomer that forms the polymer having the glass transition temperature, for example, C such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, etc._1-4Mention may be made of alkyl-methacrylates and monomers copolymerizable with these methacrylates. C_1-4Of the alkyl-methacrylates, methyl methacrylate is preferred. C_1-4Examples of monomers copolymerizable with alkyl methacrylate include alkyl acrylates such as ethyl acrylate and butyl acrylate, aromatic vinyls such as styrene, vinyl toluene, and α-methyl styrene, aromatic vinylidene, acrylonitrile, and methacrylonitrile. And vinyl monomers such as vinyl cyanide and vinylidene cyanide. Preferred copolymerizable monomers include ethyl acrylate, styrene, acrylonitrile and the like. These monomers are C_1-4Alkyl-methacrylate (such as methyl methacrylate) alone or C_1-4Used as a mixture of an alkyl-methacrylate (such as methyl methacrylate) and a copolymerizable monomer.
[0033]
In the polyacetal resin composition of the present invention, by introducing functional groups such as carboxyl group, acid anhydride group, epoxy group, amide group and hydroxyl group into the shell of the core-shell polymer, the characteristics of the polyacetal and core-shell polymer are effectively expressed. it can. Introduction of these functional groups into the shell can be carried out by copolymerization of a monomer constituting the shell and a polymerizable monomer having the functional group, or by treatment of the produced polymer.
[0034]
Examples of the polymerizable monomer having a carboxyl group include acrylic acid, methacrylic acid, and unsaturated dicarboxylic acid. Examples of the unsaturated dicarboxylic acid include maleic acid, fumaric acid, itaconic acid, citraconic acid, mesaconic acid, aconitic acid, and methylmalonic acid, and itaconic acid is preferred.
[0035]
The introduction of an acid anhydride group includes various methods such as heat-drying a core-shell polymer in which an unsaturated dicarboxylic acid residue is introduced into a shell by copolymerization under an inert gas atmosphere, heat treatment through an extruder, and the use of a dehydrating agent. The dehydration treatment can be carried out by the above method to convert at least a part of the carboxyl groups into acid anhydride groups.
[0036]
Examples of the polymerizable monomer having an epoxy group include glycidyl (meth) acrylate, and glycidyl methacrylate is often used.
[0037]
Examples of the polymerizable monomer having a hydroxyl group include hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate, and hydroxyethyl methacrylate is preferably used.
[0038]
The amount of the polymerizable monomer having a functional group is, for example, 0.1 to 20% by weight, preferably 0.5 to 15% by weight, more preferably 1 to 10% by weight, based on the whole monomer constituting the shell. Degree.
[0039]
The ratio between the core and the shell can be selected within a range not impairing the impact resistance. For example, core / shell = 40/60 to 95/5 (% by weight), preferably 50/50 to 90/10 (% by weight) More preferably, it is about 60 / 40-80 / 20 (weight%).
[0040]
In the core-shell polymer, an intermediate phase may exist between the core and the shell. The intermediate phase forms various polymerizable compounds, for example, polymerizable monomers having functional groups such as glycidyl (meth) acrylate, (meth) acrylic acid, hydroxyethyl (meth) acrylate, and glassy polymers such as methyl methacrylate. It can be formed by polymerizing a polymerizable monomer, a polymerizable monomer that forms a rubbery polymer such as butyl acrylate, and the like at an appropriate stage of seed multistage emulsion polymerization. The intermediate phase can be variously selected according to the properties of the desired core-shell polymer, and the proportion of the polymerizable monomer that forms the intermediate phase can also be appropriately selected according to the polymerizable monomer. For example, the entire monomer constituting the core-shell polymer 1 to 50% by weight, preferably 5 to 30% by weight. When the intermediate phase is a glassy polymer, the intermediate phase can be regarded as a part of the shell, and when the intermediate phase is a rubbery polymer, it can be regarded as a part of the core.
[0041]
The structure of the core-shell polymer having such an intermediate phase may be, for example, a multilayer structure in which a layer is interposed between the core and the shell, or a salami structure in which the intermediate phase is dispersed in the form of particles in the core. In a core-shell polymer having a salami structure, in a more extreme case, the dispersed intermediate phase may form a core at the center of the core. The core-shell polymer having such a structure may be formed when an aromatic vinyl monomer typified by styrene is used as a constituent monomer of the intermediate phase. When a core-shell polymer having an intermediate phase is used, in addition to impact resistance, bending elastic modulus, heat distortion temperature and appearance (inhibition of gloss, change in color tone due to change in refractive index) may be improved.
[0042]
The ratio of the core-shell polymer can be selected within a range that can improve impact resistance and does not impair the properties of the polyacetal resin. For example, 1 to 100 parts by weight, preferably 5 to 75 parts by weight with respect to 100 parts by weight of the polyacetal resin. More preferably, it is about 10 to 60 parts by weight, and usually about 15 to 50 parts by weight (particularly 20 to 40 parts by weight). If the addition amount of the core-shell polymer is small, the impact resistance of the polyacetal resin composition may not be improved so much, and if it is too large, the rigidity and heat resistance of the polyacetal resin composition may be impaired.
[0043]
In the preferred core-shell polymer, substantially free anions are not detected. The core-shell polymer in which substantially free anions are not detected means a core-shell polymer in which no anion is detected by a normal anion qualitative test. For example, as a measuring method, 5 g of a sample (core-shell polymer) is weighed in a flask, 20 ml of ion-exchanged water is added, and the mixture is stirred for 3 hours with a magnetic stirrer. The filtrate filtered with 5C filter paper was divided into two, 0.5 ml of 1% barium chloride aqueous solution was added to one side, and the occurrence of turbidity was comparatively observed (sulfate ion qualitative test). After the same treatment, 1% The presence of anions can be confirmed by a method (qualitative test of halogen ions) in which a 0.1N silver nitrate aqueous solution is added in place of the barium chloride aqueous solution and the occurrence of turbidity is comparatively observed. Preferred core-shell polymers are core-shell polymers in which these anions are not present at all.
[0044]
The core-shell polymer can be obtained by polymerizing a monomer by multistage emulsion polymerization in the presence of various emulsifiers such as an anionic surfactant, a cationic surfactant, and a nonionic surfactant. Depending on the type, the stability of the polyacetal resin may be adversely affected. Therefore, it is advantageous to use a core-shell polymer emulsion-polymerized in the presence of a nonionic surfactant as an emulsifier. The nonionic surfactant may be any of a low molecular weight surfactant, an oligomer type surfactant, and a high molecular weight surfactant. Nonionic surfactants include, for example, ethers such as polyoxyethylene alkylphenyl ether (polyoxyethylene nonylphenyl ether, etc.) and polyoxyethylene long chain alkyl ether (polyoxyethylene stearyl ether, polyoxyethylene lauryl ether, etc.). Surfactants, ester surfactants such as polyoxyethylene higher fatty acid esters (such as polyoxyethylene monostearate), sorbitan ester types such as polyoxyethylene sorbitan higher fatty acid esters (such as polyoxyethylene sorbitan monolaurate) Examples thereof include surfactants and block copolymers such as polyoxyethylene polyoxypropylene block copolymers. These surfactants can be used alone or in combination. In addition, you may use a nonionic surfactant in combination with an anionic surfactant, if it is a range which does not impair the stability of a polyacetal resin.
[0045]
The amount of the surfactant used can be appropriately selected within a range that does not impair the stability of emulsion polymerization, and can be selected, for example, from a range of about 0.1 to 10% by weight based on the total amount of monomers.
[0046]
Furthermore, as a polymerization initiator in emulsion polymerization, for example, persulfates such as potassium persulfate and ammonium persulfate may be used. In order to improve the stability of the polyacetal resin, an anionic component is introduced into the core-shell polymer. Initiators that can inhibit the polymerization, for example, peroxides such as hydrogen peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, azobisisobutyronitrile, dimethyl 2,2'-azobisisobutyrate, 2,2'- It is advantageous to use an azo polymerization initiator such as azobis (2-aminopropane) dihydrochloride. The polymerization initiator may be a redox polymerization initiator composed of the polymerization initiator and a reducing agent.
[0047]
In order to improve the hinge properties of the polyacetal resin and the core-shell polymer, the core-shell polymer preferably contains a higher saturated fatty acid amide, particularly a saturated fatty acid bisamide, as a lubricant. Saturated fatty acid bisamide can be represented by the following formula.
[0048]
R^1a-CONH-R²-NHCO-R^1b
(Wherein R^1aAnd R^1bAre the same or different and each represents an aliphatic alkyl group having 10 to 26 carbon atoms, a substituted alkyl group, an aryl group, or a substituted aryl group;²Represents a divalent hydrocarbon group having 1 to 12 carbon atoms)
R^1aAnd R^1bIs usually an aliphatic alkyl group that constitutes a saturated fatty acid. Examples of saturated fatty acids include undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, arachidic acid , Behenic acid, lignoceric acid, and serotic acid. Preferred saturated fatty acids include C such as stearic acid._12-22Contains saturated higher fatty acids. R²Is usually an alkylene group such as methylene, ethylene, trimethylene, tetramethylene, pentamethylene or hexamethylene, with a methylene group or ethylene group being preferred. Preferred saturated fatty acid bisamides include methylene bis stearic acid amide and ethylene bis stearic acid amide.
[0049]
The amount of fatty acid amide (particularly fatty acid bisamide) used is about 0.3 to 5 parts by weight, preferably about 1 to 5 parts by weight, particularly about 2 to 4 parts by weight, based on 100 parts by weight of the core-shell polymer.
[0050]
[Inhibitor]
Among the formaldehyde inhibitors, examples of the urea derivative include N-substituted urea substituted with a substituent such as an alkyl group [for example, N-C such as N-methyl and N-ethyl forms._1-6Alkyl compounds, alkylenediureas (for example, C such as methylenediurea)_1-6Alkylene diurea etc.)], urea condensates and the like. The urea condensate may be acyclic or cyclic. Examples of the acyclic condensate include urea dimers (for example, biuret and biurea), urea multimers, urea and aldehyde. Condensates with compounds are included. As this condensate, C_1-6Examples include condensates with aldehydes, such as acyclic condensates of urea and isobutyraldehyde (such as isobutylidene diurea) and acyclic condensates of urea and formaldehyde. In the acyclic condensate of urea and formaldehyde, one or a plurality of urea units may be condensed, and (n + 1) urea units may be condensed via n methylene chains (n Is an integer of 1 or more). The acyclic condensates can be used alone or in combination of two or more. This mixture is commercially available from Mitsui Chemicals, for example, as form nitrogen (a mixture of methylenediurea, dimethylenetriurea, trimethylenetetraurea, etc.). The urea derivative may be a urea resin. The urea derivatives can be used alone or in combination of two or more.
[0051]
Preferred urea derivatives include ureido derivatives such as monoureido and diureido, or derivatives thereof. Furthermore, urea derivatives include acyclic ureido or cyclic ureido.
[0052]
As an acyclic monoureido, C_2-6Ureido acids of dicarboxylic acids [eg ureido acid (oxalulic acid) of oxalic acid, ureido acid of malonic acid (malonuric acid, etc.)] or derivatives thereof (eg acid amides of ureido acid), or carboxylic acids having a ureido group [For example, ureido group-containing C such as ureidoformic acid and ureidoacetic acid_1-6Carbamide group-containing C such as monocarboxylic acid, ureidosuccinic acid (carbamyl aspartic acid)_2-6Dicarboxylic acid], or carbamide group-containing acid amides (alophanoic acid anilide, allophanic acid amide, etc.) and carbamide group-containing esters (alophane acid ester, etc.). As an acyclic diureido, C_2-6Examples thereof include carboxylic acid diureides [for example, acetic acid diureido (allantoic acid) and the like].
[0053]
Examples of the cyclic monoureide include a cyclic condensate of urea and acetaldehyde (for example, clothylidene diurea), allantoin, and derivatives thereof.
[0054]
Monoureido or diureido, particularly cyclic ureido derivatives, are metal salts such as alkali metal salts (Group 1A metal salts of the periodic table such as Li, Na, K), alkaline earth metal salts (Mg, Ca, Sr, Ba, etc.). Periodic Table 2A Group Metal Salt), Periodic Table 1B Group Metal Salt (Salt with Cu, Ag, etc.), Periodic Table 2B Group Metal Salt (Salt with Zn, etc.), Periodic Table 3B Group Metal Salt (Al, Ga, In) Etc.), metal salts such as periodic table group 4B metal salts (salts with Sn, Pb, etc.), periodic table group 8 metal salts (salts with Fe, Co, Ni, Pd, Pt, etc.) A tetravalent metal salt) may be formed.
[0055]
Particularly preferred cyclic ureido derivatives include allantoin and derivatives thereof. For the allantoin derivative, reference can be made to the document “DICTIONARY OF ORGANIC COMPOUNDS Vol. 1, p60 (1965 EYRE & SPOTTISWOODE-PUBLISHERS-LTD)”. Examples of allantoin derivatives include substituted allantoin derivatives substituted with various substituents such as alkyl groups, cycloalkyl groups, and aryl groups (for example, 1-methyl, 3-methyl, 3-ethyl, and 5-methyl derivatives). 1,3-dimethyl, 1,6-dimethyl, 1,8-dimethyl, 3,8-dimethyl, 1,3,6-trimethyl, 1,3,8-trimethyl and the like, Di or Tri-C_1-4Alkyl-substituted products, aryl-substituted products such as 5-phenyl compounds), and metal salts thereof [alkali metal salts (group 1A metal salts of periodic table), alkaline earth metal salts (group 2A metal salts of periodic table), periodic tables] Salt with group 1B metal, salt with periodic table group 2B metal, salt with periodic table group 3B metal, salt with periodic table group 4B metal, salt with periodic table group 8 metal, etc.], allantoin and aldehyde compound A reaction product of an allantoin and a nitrogen-containing compound (such as an amino group or imino group-containing compound) [for example, 2- Compound with pyrrolidone-5-carboxylate (salt, molecular compound (complex), etc.), Compound with allantoin and imidazole compound (salt, molecular compound (complex), etc.)], Machine acid salt, or the like can also be used. Specific examples of allantoin metal salts include allantoin dihydroxyaluminum and allantoin chlorohydroxyaluminum, and examples of the reaction product with an amino group or imino group-containing compound include allantoinsodium-dl pyrrolidonecarboxylate. .
[0056]
JP-A-51-36453 can be referred to for the compound of allantoin and 2-pyrrolidone-5-carboxylate, and JP-A-52-102412 for the reaction product of allantoin and basic amino acid. Reference can be made to JP-A-52-25771, JP-A-52-25772, JP-A-52-31072, JP-A-51-19771. For the compound of allantoin and imidazole compound, reference can be made to JP-A-57-118569. The three-dimensional structure of allantoin and its derivatives is not particularly limited, and may be any of d-form, l-form and dl-form. These allantoin and its derivative can be used individually or in combination of 2 or more types.
[0057]
For the amidine derivative, RC (= NH) NH₂Amidine containing a structural unit represented by (R represents a hydrogen atom, an alkyl group, or an acyl group) and derivatives thereof are included. The structure of the amidine derivative may be non-cyclic or non-melamine cyclic amidine. Furthermore, the amidine derivatives also include guanidines (guanidine or derivatives thereof) in which R is an amino group, and the structure of guanidines may be acyclic or cyclic. Acyclic amidine includes, for example, amidine or a derivative thereof. Preferred amidines are guanidines, and acyclic guanidine includes, for example, glycosylamine, guanolin, creatine, or derivatives thereof.
[0058]
Preferred guanidines are cyclic guanidines. Cyclic guanidine is -R₁NC (= NH) NR₂-(R₁And R₂Are the same or different and each represents a hydrogen atom, an alkyl group, or an acyl group. ) As a structural unit of the ring, and is not particularly affected by the size of the ring, but a 5-membered or 6-membered ring compound is preferable. In the above formula, R₁And R₂As the alkyl group represented by C,_1-4Alkyl groups, particularly methyl or ethyl groups, acyl groups include C_1-4An acyl group, particularly a formyl group, an acetyl group, or a propionyl group is preferable, and a hydrogen atom is particularly preferable.
[0059]
Preferred cyclic guanidines include, as a 5-membered ring nitrogen-containing compound, glycocyamidine or a derivative thereof (for example, glycocyamidine, thioglycocyanidin, creatinine, 4-methylglycocyanidin, 4,4-glycocyanidin, etc. ), Oxalylguanidine or a cyclic guanidine similar to the structure thereof (for example, oxalylguanidine, 2,4-diiminoparabanic acid, 2,4,5-triiminoparabanic acid, etc.), two oxo groups (= O) of urazole Of these, compounds in which at least one oxo group (═O) is substituted with an imino group (═NH) (for example, iminourazole, iminothiourazole, guanazine, etc.) can be exemplified. Preferred 6-membered ring nitrogen-containing compounds include non-melamine compounds such as isocyanuric imides or derivatives thereof (for example, isoammelide, isoammelin, or N-substituted products thereof), cyclic guanidines such as malonylguanidine and tartronylguanidine. Or its derivative | guide_body, cyclic guanidine compounds, such as mesoxalyl guanidine, etc. can be illustrated.
[0060]
Among the guanidines, glycocyanidine or a derivative thereof is particularly preferable. The most preferred cyclic nitrogen-containing compounds include glycocyanidines (such as creatinine).
[0061]
The urea, urea derivative, or amidine derivative may be used alone as an inhibitor, or may be used in combination of two or more.
[0062]
The ratio of the inhibitor is, for example, 0.01 to 10 parts by weight (for example, 0.01 to 5 parts by weight), preferably 0.02 to 5 parts by weight, and more preferably 0.00 to 100 parts by weight of the polyacetal resin. Even if it is about 03-2.5 weight part and about 0.03-1.5 weight part (for example, 0.1-1.5 weight part), the production | generation of formaldehyde can be suppressed notably.
[0063]
[Other ingredients]
The inhibitor alone can provide significant stability to the polyacetal resin, but can be an antioxidant, a nitrogen-containing compound (particularly a basic nitrogen-containing compound), an alkali or an alkaline earth metal (particularly , Organic carboxylic acid metal salts, metal oxides, metal inorganic acid salts such as metal carbonates) and the like may be used singly or in combination.
[0064]
Antioxidants include, for example, phenolic (such as hindered phenols), amine, phosphorus, sulfur, hydroquinone, and quinoline antioxidants.
[0065]
Phenol antioxidants include hindered phenols such as 2,2'-methylenebis (4-methyl-6-t-butylphenol), 4,4'-methylenebis (2,6-di-t-butylphenol). 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 2,6-di-tert-butyl-p-cresol, 1,3,5-trimethyl-2,4,6-tris (3 , 5-di-t-butyl-4-hydroxybenzyl) benzene, 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis [ 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4) Hydroxyphenyl) propionate], n-octadecyl-3- (4 ′, 5′-di-t-butylphenol) propionate, n-octadecyl-3- (4′-hydroxy-3 ′, 5′-di-t-butylphenol) ) Propionate, stearyl-2- (3,5-di-t-butyl-4-hydroxyphenol) propionate, distearyl-3,5-di-t-butyl-4-hydroxybenzylphosphonate, 2-t-butyl- 6- (3-tert-butyl-5-methyl-2-hydroxybenzyl) -4-methylphenyl acrylate, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocin Muamido), 3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy ] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5,5] undecane, 4,4′-thiobis (3-methyl-6-tert-butylphenol), 1,1, 3-tris (2-methyl-4-hydroxy-5-tert-butylphenol) butane and the like are included.
[0066]
Examples of amine-based antioxidants include phenyl-1-naphthylamine, phenyl-2-naphthylamine, N, N′-diphenyl-1,4-phenylenediamine, and N-phenyl-N′-cyclohexyl-1,4-phenylene. Diamines; 4,4′-di (α, α-dimethylbenzyl) diphenylamine and the like.
[0067]
Examples of phosphorus antioxidants include triisodecyl phosphite, triphenyl phosphite, trisnonyl phenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, 2,2-methylenebis (4,6-di-). t-butylphenyl) octyl phosphite, 4,4′-butylidenebis (3-methyl-6-tert-butylphenyl) ditridecyl phosphite, tris (2,4-di-t-butylphenyl) phosphite, tris ( 2-t-butyl-4-methylphenyl) phosphite, tris (2,4-di-t-amylphenyl) phosphite, tris (2-t-butylphenyl) phosphite, bis (2-t-butylphenyl) ) Phenyl phosphite, tris [2- (1,1-dimethylpropyl) -phenyl] Phosphites, tris [2,4- (1,1-dimethylpropyl) -phenyl] phosphite, tris (2-cyclohexylphenyl) phosphite, tris (2-tert-butyl-4-phenylphenyl) phosphite Phyto; triethylphosphine, tripropylphosphine, tributylphosphine, tricyclohexylphosphine, diphenylvinylphosphine, allyldiphenylphosphine, triphenylphosphine, methylphenyl-p-anisylphosphine, p-anisyldiphenylphosphine, p-tolyldiphenylphosphine, Di-p-anisylphenylphosphine, di-p-tolylphenylphosphine, tri-m-aminophenylphosphine, tri-2,4-dimethylphenylphosphine, tri-2,4,6-tri Tylphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tri-o-anisylphosphine, tri-p-anisylphosphine, 1,4-bis (diphenylphosphino ) A phosphine compound such as butane is included.
[0068]
Examples of the hydroquinone antioxidant include 2,5-di-t-butylhydroquinone, and examples of the quinoline antioxidant include 6-ethoxy-2,2,4-trimethyl-1,2. -Dihydroquinoline and the like are included, and sulfur-based antioxidants include, for example, dilauryl thiodipropionate, distearyl thiodipropionate, and the like.
[0069]
These antioxidants can be used alone or in combination of two or more.
[0070]
Preferred antioxidants include phenolic antioxidants (particularly hindered phenols). Among hindered phenols, in particular, polyol-poly [(branched C_3-6Alkyl group and hydroxy group-substituted phenyl) propionate], for example, 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]_2-10Alkylenediol-bis [3- (3,5-di-branched C_3-6Alkyl-4-hydroxyphenyl) propionate]; di- or trioxy C such as, for example, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate]_2-4Alkylenediol-bis [3- (3,5-di-branched C_3-6Alkyl-4-hydroxyphenyl) propionate]; for example, glycerol tris [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]_3-8Alkanetriol-bis [3- (3,5-di-branched C_3-6Alkyl-4-hydroxyphenyl) propionate]; for example C such as pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate]_4-8Alkanetetraoltetrakis [3- (3,5-di-branched C_3-6Alkyl-4-hydroxyphenyl) propionate] and the like.
[0071]
These antioxidants can be used alone or in combination of two or more. The content of the antioxidant is, for example, in the range of 0.01 to 5 parts by weight, preferably 0.05 to 2.5 parts by weight, particularly about 0.1 to 1 part by weight with respect to 100 parts by weight of the polyacetal resin. You can choose from.
[0072]
The basic nitrogen-containing compound includes a low molecular compound and a high molecular compound (nitrogen-containing resin). Examples of the nitrogen-containing low molecular weight compound include aliphatic amines such as monoethanolamine and diethanolamine, and aromatic amines (aromatic secondary amines or tertiary amines such as o-toluidine, p-toluidine, and p-phenylenediamine). Amines), amide compounds (malonamide, polycarboxylic acid amides such as isophthalic acid diamide, p-aminobenzamide, etc.), hydrazine or derivatives thereof (hydrazides such as hydrazine, hydrazone, polyhydric carboxylic acid hydrazide, etc.), polyaminotriazines ( Examples thereof include guanamines such as guanamine, acetoguanamine, benzoguanamine or derivatives thereof, melamine or derivatives thereof, uracil or derivatives thereof (uracil, uridine, etc.), cytosine or derivatives thereof (cytosine, cytidine, etc.), and the like.
[0073]
Nitrogen-containing resins include, for example, amino resins produced by reaction with formaldehyde (condensation resins such as guanamine resins, melamine resins and guanidine resins, phenol-melamine resins, benzoguanamine-melamine resins, aromatic polyamine-melamine resins, etc. Condensation resin, etc.), aromatic amine-formaldehyde resin (aniline resin, etc.), polyamide resin (eg, nylon 3, nylon 6, nylon 66, nylon 11, nylon 12, nylon MXD6, nylon 4-6, nylon 6-10, Nylon 6-11, Nylon 6-12, Nylon 6-66-610 or other single or copolymerized polyamides, substituted polyamides having a methylol group or an alkoxymethyl group), polyesteramides, polyamideimides, polyacrylamides, polyacrylamides, etc. Iminothioetherified, such as polyurethane can be exemplified.
[0074]
Preferred nitrogen-containing compounds include polyaminotriazines (melamine or derivatives thereof) and nitrogen-containing resins (amino resins such as melamine resins, polyamide resins, etc.). In particular, melamine, amino resins (such as melamine resin), and polyamide resins are preferable, and amino resins, particularly crosslinked amino resins are preferable. Furthermore, a melamine resin (melamine-formaldehyde resin), particularly a crosslinked melamine resin is preferable.
[0075]
These nitrogen-containing compounds can be used alone or in combination of two or more. The amount of the nitrogen-containing compound used is, for example, 0.01-5 parts by weight, preferably 0.05-2. It can be selected from a range of about 5 parts by weight (particularly 0.1 to 1 part by weight).
[0076]
Examples of the alkali or alkaline earth metal compound include carboxylic acid and alkali metal (sodium, potassium, etc.) or alkaline earth metal (magnesium, calcium, barium, etc.) salt (carboxylic acid metal salt); hydroxide; CaO, Metal oxides such as MgO; CaCO_Three, MgCO_ThreeExamples thereof include inorganic acid salts such as metal carbonates, silicates, borates and phosphates; alkoxides (methoxides and ethoxides of the metals).
[0077]
As the carboxylic acid constituting the carboxylate, a saturated or unsaturated aliphatic carboxylic acid having about 1 to 36 carbon atoms can be used. Further, these aliphatic carboxylic acids may have a hydroxyl group. Examples of the saturated aliphatic carboxylic acid include acetic acid, propionic acid, butyric acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, montanic acid, melicic acid, celloplastin Saturated C such as acid_1-36Monocarboxylic acids and polycarboxylic acids [for example, saturated C such as oxalic acid, malonic acid, succinic acid, adipic acid, etc._2-36Saturated C such as dicarboxylic acid, tricarballylic acid, butanetricarboxylic acid_6-36Tricarboxylic acid] or oxyacids thereof (for example, lactic acid, hydroxybutyric acid, hydroxylauric acid, hydroxypalmitic acid, hydroxystearic acid, citric acid, etc.). Examples of unsaturated aliphatic carboxylic acids include unsaturated C such as undecylenic acid, oleic acid, elaidic acid, cetreic acid, erucic acid, brassic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid._3-36Examples thereof include carboxylic acids or oxyacids thereof (for example, propiolic acid, stearic acid, etc.).
[0078]
The alkali or alkaline earth metal compounds can be used alone or in combination of two or more, and the proportion thereof is, for example, 0.001 to 10 parts by weight, preferably 0.001 to 5 parts per 100 parts by weight of the polyacetal resin. It can be selected from a range of about parts by weight (particularly 0.001 to 2 parts by weight).
[0079]
The antioxidant, nitrogen-containing compound and alkali or alkaline earth metal compound may be used in combination.
[0080]
A weather resistance (light) stabilizer may be added to the resin composition of the present invention. Weather resistant (light) stabilizers include benzotriazole compounds [2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butyl]. Hydroxyl group-containing benzotriazoles such as phenyl) benzotriazole and 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] benzotriazole (for example, benzotriazoles having a hydroxyl group-substituted aryl group) ), Etc.], benzophenone compounds [hydroxyl group-containing benzophenones such as 2,4-dihydroxybenzophenone], aromatic benzoate compounds [alkylphenyl salicylates such as pt-butylphenyl salicylate], cyanoacrylate compounds [2-ethylhexyl-2 -Cyano group-containing diphenyl acrylates such as cyano-3,3-diphenyl acrylate, etc.], oxalic acid anilide compounds [N- (2-ethylphenyl) -N '-(2-ethoxy-5-t-butylphenyl) Oxalic acid diamides such as oxalic acid diamide], hindered amine compounds [piperidine derivatives having sterically hindered groups (4-acetoxy-2,2,6,6-tetramethylpiperidine, bis (2,2,6,6) -Tetramethyl-4-piperidyl) sebacate), high molecular weight piperidine derivative polycondensate (dimethyl-1- (2-hydroxyethyl) succinate-4-hydroxy-2,2,6,6-tetramethylpiperidine heavy) And the like). These weather resistance (light) stabilizers can be used alone or in combination of two or more.
[0081]
The amount of the weathering (light) stabilizer added is, for example, 0.01 to 5 parts by weight (for example, 0.01 to 3 parts by weight), preferably 0.01 to 2 parts by weight with respect to 100 parts by weight of the polyacetal resin. More preferably, it is about 0.1 to 2 parts by weight (for example, 0.1 to 1.5 parts by weight).
[0082]
Moreover, it is also possible to mix a coloring agent with the polyacetal resin composition of this invention further. Various dyes or pigments can be used as the colorant. The dye is preferably a solvent dye, and examples thereof include azo dyes, anthraquinone dyes, phthalocyanine dyes, and naphthoquinone dyes. As the pigment, any of inorganic pigments and organic pigments can be used. Inorganic pigments include titanium pigments, zinc pigments, carbon black (furnace black, channel black, acetylene black, ketjen black, etc.), iron pigments, molybdenum pigments, cadmium pigments, lead pigments, cobalt pigments And an organic pigment such as azo pigment, anthraquinone pigment, phthalocyanine pigment, quinacridone pigment, perylene pigment, perinone pigment, isoindoline pigment, dioxazine pigment, or Examples include selenium pigments. The above colorants may be used alone or in combination with a plurality of colorants. When a colorant having a high light shielding effect such as carbon black or titanium white (titanium oxide) is used, weather resistance (light) can be improved.
[0083]
Content of a coloring agent is 0-5 weight part (for example, 0.01-5 weight part) with respect to 100 weight part of polyacetal resin, for example, Preferably it is 0.1-4 weight part, More preferably, it is 0.00. About 3 to 3 parts by weight.
[0084]
In the resin composition of the present invention, if necessary, a resin such as an acrylic resin (polymethyl methacrylate or other C_1-10Alkyl (meth) acrylate homo- or copolymer), polycarbonate resin or the like may be added. Moreover, appearance defects such as cracks can be suppressed by adding surface modifiers such as fatty acid esters of mono- or polyhydric alcohols and ethers of polyhydric alcohols.
[0085]
In the polyacetal resin composition of the present invention, various additives as necessary, for example, release agents, nucleating agents, antistatic agents, flame retardants, surfactants, antibacterial agents, antifungal agents, various polymers, fillers These may be added singly or in combination of two or more.
[0086]
The polyacetal resin composition of the present invention may be a granular mixture or a molten mixture, and is prepared by mixing a polyacetal resin, a core-shell polymer, an inhibitor, and, if necessary, other additives by a conventional method. it can. For example, (1) mixing each component, kneading with a uniaxial or biaxial extruder and extruding to prepare pellets, and (2) once preparing pellets (master batch) with different compositions , A method of mixing (diluting) a predetermined amount of the pellet and subjecting it to molding to obtain a molded product having a predetermined composition. (3) After applying an inhibitor to the pellet of polyacetal resin by spraying or the like, molding, A method for obtaining a molded article having a composition can be employed. Also, in the preparation of a composition used for a molded product, a polyacetal resin powder (for example, a powder obtained by pulverizing a part or all of a polyacetal resin) and other components (such as a urea derivative) are mixed. When melt-kneaded, it is advantageous to improve the dispersion of the additive.
[0087]
The polyacetal resin composition of the present invention can improve the working environment by remarkably suppressing the formation of formaldehyde due to oxidation or thermal decomposition of the polyacetal resin, particularly in the molding process (particularly melt molding process). A molded article having high weld strength and weld elongation can be obtained. Further, adhesion of decomposition products to the mold (mold deposit) and leaching of decomposition products from the molded product can be remarkably suppressed, and various problems during molding can be improved. Therefore, the resin composition of the present invention can be produced by various molding products by a conventional molding method such as injection molding, extrusion molding, compression molding, blow molding, vacuum molding, foam molding, rotational molding, gas injection molding and the like. Is useful for molding.
[0088]
The molded article of the present invention composed of the polyacetal resin composition contains the inhibitor, and the amount of formaldehyde generated is extremely small. That is, a molded article made of the conventional polyacetal resin containing a stabilizer such as an antioxidant produces a relatively large amount of formaldehyde, and pollutes the living environment and work environment in addition to corrosion and discoloration. For example, the amount of formaldehyde generated from a commercially available polyacetal resin molded product is 1 cm in surface area in a dry type (in a constant temperature dry atmosphere).²The surface area is about 2 to 5 μg, and in a wet condition (in a constant temperature and humid atmosphere), the surface area is 1 cm.²It is about 3 to 6 μg per unit. Moreover, even if the molding conditions are controlled, the surface area is 1 cm in a dry type (under a constant temperature drying atmosphere).²1.5 μg or less per surface area in a wet (constant temperature and humidity atmosphere) 1 cm surface area²It is difficult to obtain a molded product of 2.5 μg or less per unit.
[0089]
In contrast, the polyacetal resin molded product of the present invention has a dry formaldehyde generation amount of 1 cm in surface area of the molded product.²1.5 μg or less (about 0 to 1 μg), preferably 0 to 1.3 μg, more preferably about 0 to 1.2 μg, and usually about 0.01 to 1.2 μg. In addition, when wet, the amount of formaldehyde generated is 1 cm of surface area of the molded product.²2.5 μg or less (about 0 to 2 μg), preferably 0 to 1.7 μg, more preferably about 0 to 1.5 μg, and usually about 0.01 to 1.5 μg.
[0090]
The polyacetal resin molded article of the present invention only needs to have the formaldehyde generation amount in either one of the dry type and the wet type, and usually has the formaldehyde generation amount in both the dry type and the wet type.
[0091]
The amount of formaldehyde generated in the dry method can be measured as follows.
[0092]
After cutting the polyacetal resin molded product as necessary and measuring the surface area, an appropriate amount of the molded product (for example, a surface area of 10 to 50 cm)²Is placed in a closed container (capacity 20 ml) and left at a temperature of 80 ° C. for 24 hours. Thereafter, 5 ml of water is poured into this sealed container, and the amount of formalin in this aqueous solution is determined according to JIS K0102, 29 (formaldehyde term), and the amount of formaldehyde generated per surface area of the molded product (μg / cm²)
[0093]
Moreover, the amount of formaldehyde generated in the wet state can be measured as follows.
[0094]
After cutting the polyacetal resin molded product as necessary and measuring the surface area, an appropriate amount of the molded product (for example, a surface area of 10 to 100 cm)²Is suspended on the lid of a sealed container (capacity 1 L) containing 50 ml of distilled water and sealed, and left in a constant temperature bath at a temperature of 60 ° C. for 3 hours. Then, it is allowed to stand at room temperature for 1 hour, and the formalin amount of the aqueous solution in the sealed container is determined according to JIS K0102, 29 (formaldehyde term), and the amount of formaldehyde generated per surface area of the molded product (μg / cm²)
[0095]
The numerical definition of the amount of formaldehyde generated in the present invention is that the molded article of the polyacetal resin composition containing conventional additives (ordinary stabilizers, release agents, etc.) as long as the polyacetal resin, core-shell polymer, and inhibitor are included. In addition to the molded article of the composition containing not only the inorganic filler and other polymers, the molded article (for example, 50 to 100%) of the surface of the molded article is composed of a polyacetal resin (for example, The present invention can also be applied to multicolor molded products and coated molded products.
[0096]
The molded product of the present invention can be used for any application in which formaldehyde is harmful (for example, knobs and levers as bicycle parts), and for applications that require impact resistance, such as the automotive field, It is suitably used as parts / members in electronic parts such as mechanical parts (active parts and passive parts), building materials / piping, daily necessities (life) / cosmetics, and medical (medical / therapeutic).
[0097]
More specifically, the mechanical parts in the automotive field include inner handles, fael trunk openers, seat belt buckles, assist wraps, various interior parts such as switches, knobs, levers, clips, electrical system parts such as meters and connectors, Examples include in-vehicle electrical and electronic parts such as audio equipment and car navigation equipment, parts that come into contact with metal, such as window regulator carrier plates, door lock actuator parts, mirror parts, wiper motor system parts, fuel system parts, etc. it can.
[0098]
Mechanical parts in the electrical / electronic field are parts or members of equipment that is made of polyacetal resin molding and has many metal contacts [for example, audio equipment such as cassette tape recorders, VTRs (video tape recorders), 8mm video , Video equipment such as video cameras, or OA (office automation) equipment such as copiers, facsimiles, word processors, and computers, as well as toys, telephones, keyboards attached to computers, etc. that operate with motors, driving force ] Etc. can be illustrated. Specifically, a chassis (base), a gear, a lever, a cam, a pulley, a bearing, etc. are mentioned. Furthermore, optical and magnetic media components (for example, metal thin film magnetic tape cassettes, magnetic disk cartridges, magneto-optical disk cartridges, etc.), at least partly composed of polyacetal resin molded products, more specifically, metal tape cassettes for music, The present invention can also be applied to a digital audio tape cassette, an 8 mm video tape cassette, a floppy disk cartridge, a mini disk cartridge, and the like. Specific examples of optical and magnetic media parts include tape cassette parts (tape cassette body, reel, hub, guide, roller, stopper, lid, etc.), disk cartridge parts (disk cartridge body (case), shutter, clamping Plate).
[0099]
Furthermore, the polyacetal resin molded product of the present invention includes lighting equipment, fittings, piping, faucets, faucets, toilet peripheral parts and other building materials and piping parts, stationery, lip balm and lipstick containers, washing machines, water purifiers, spray nozzles, It is suitably used for a wide range of life-related parts, makeup-related parts, and medical-related parts such as spray containers, aerosol containers, general containers, and needle holders.
[0100]
【The invention's effect】
Since the polyacetal resin composition of the present invention contains a core-shell polymer and an inhibitor, the impact resistance and thermal stability (particularly, melt stability during molding) of the polyacetal resin can be greatly improved. Moreover, the amount of formaldehyde generated can be suppressed to a very low level by adding a small amount of an inhibitor, and the working environment can be greatly improved and the impact resistance can be greatly improved. Furthermore, it is possible to suppress the formation of formaldehyde even under harsh conditions, and to prevent the decomposition product from adhering to the mold (mold deposit), the leaching of the decomposition product of the molded product and the thermal deterioration of the molded product. Quality and formability can be improved.
[0101]
【Example】
Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.
[0102]
In Examples and Comparative Examples, the amount of formaldehyde generated from dry and wet molded articles and the weather resistance (light) were evaluated as follows.
[0103]
[Formaldehyde generation amount from dry molded products]
10 test pieces (2mm x 2mm x 50mm) (total surface area about 40cm)²) Was placed in a sealed container (capacity 20 ml), heated in a thermostatic chamber at a temperature of 80 ° C. for 24 hours, then air-cooled to room temperature, and 5 ml of distilled water was injected with a syringe. The amount of formaldehyde in this aqueous solution was quantified according to JIS K0102, 29 (formaldehyde term), and the amount of formaldehyde gas generated per surface area (μg / cm²) Was calculated.
[0104]
[Formaldehyde generation from wet molded products]
Test piece (100mm x 40mm x 2mm) obtained by cutting out four sides from a flat molded product (120mm x 120mm x 2mm); total surface area 85.6cm²Is hung on the lid of a polyethylene bottle (capacity 1 L) containing 50 ml of distilled water, sealed, left in a thermostatic bath at a temperature of 60 ° C. for 3 hours, and then allowed to stand at room temperature for 1 hour. The amount of formalin in the aqueous solution in the polyethylene bottle was determined according to JISK0102, 29 (formaldehyde term), and the amount of formaldehyde generated per surface area (μg / cm²) Was calculated.
[0105]
The polyacetal resins, core-shell polymers, urea derivatives, antioxidants and nitrogen-containing compounds used in the examples and comparative examples are as follows.
[0106]
1. Polyacetal resin
(A): Polyacetal resin copolymer
(“Duracon” manufactured by Polyplastics Co., Ltd.)
2. Core shell polymer
(B-1): “STAPHYLOID PO-0135” [manufactured by Takeda Pharmaceutical Co., Ltd.]
(B-2): “STAPHYLOID PO-0270” [manufactured by Takeda Pharmaceutical Co., Ltd.]
(B-3): “Paraloid KCA-102” [Kureha Chemical Co., Ltd.]
(B-4): “Metabrene S-2001” [Mitsubishi Rayon Co., Ltd.]
(B-5): Core shell polymer A
(B-6): Core shell polymer B
[Preparation of core-shell polymer A (b-5) and core-shell polymer B (b-6)]
A polymerization vessel with a reflux condenser (capacity: 5 liters) was charged with 1200 g of deionized water, 1.68 g of 25% aqueous ammonia, 7 g of surfactant A, and 0.14 g of methacrylamide, and the mixture was heated to 70 ° C. with stirring under a nitrogen stream. The temperature rose. After adding 27.86 g of a seed monomer mixture having the following composition and dispersing for 10 minutes, 2,2-azobis (2-aminopropane) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd., V-50) 21 g of a 10% by weight aqueous solution was added and polymerized to produce seed particles.
[0107]
The surfactant A was prepared according to the method described in Example 13 of JP-A-53-10682, 155 g of methacrylic acid, 360 g of methyl methacrylate, 109 g of n-dodecylmethylcaptan, azobisisobutyro After synthesizing by polymerization using 4.4 g of nitrile and 314 g of isopropanol, the pH was adjusted to 7.5 with aqueous ammonia, and then the solid content was adjusted to 10 wt% with pure water. The obtained surfactant A has an n-dodecylmethicato group at the terminal, and the ratio of the methyl methacrylate unit a to the methacrylic acid unit b is a: b = 7: 3, a + b = about 13.6.
[0108]
[Composition of seed monomer]
Ethyl acrylate 27.664 g
Allyl methacrylate 0.14 g
0.056 g of 1,4-butylene glycol diacrylate.
[0109]
Next, 7 g of methacrylamide was added, and a monomer emulsion (emulsion obtained by adding 210 g of surfactant A, 900 g of deionized water and 2.80 g of 25% aqueous ammonia to the core monomer mixture having the following composition), 2, A mixture of 21 g of a 10 wt% aqueous solution of 2'-azobis (2-aminopropane) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd., V-50) and 0.63 g of 1% aqueous ammonia was continuously added over 180 minutes. The seed polymerization was carried out.
[0110]
[Composition of monomer in core part]
2-ethylhexyl acrylate 1040.2g
Butadiene 450.0g
1,4-butylene glycol diacrylate 2.8 g
Allyl methacrylate 7.0 g.
[0111]
The temperature was raised to 80 ° C. and aged for 1 hour, and then cooled to 70 ° C.
[0112]
Next, 9 g of 10% by weight aqueous solution of 2,2′-azobis (2-aminopropane) dihydrochloride (manufactured by Wako Pure Chemical Industries, Ltd., V-50) and 0.27 g of 1% ammonia water were added, and the following composition was added: Monomer emulsion of shell part, 2,2′-azobis (2-aminopropane) dihydrochloride (Wako Pure Chemical Industries, Ltd., V-50) 12% by weight aqueous solution 12 g, 1% ammonia water 0.36 g Was continuously fed over 60 minutes to seed polymerize.
[0113]
[Composition of monomer emulsion of shell part]
Methyl methacrylate 438.8g
Ethyl acrylate 60.0g
Surfactant A 30.0g
Deionized water 500.0g
25% ammonia water 0.72g
1,4-butylene glycol diacrylate 1.2g
Methacrylamide 3.0g.
[0114]
After raising the reaction temperature to 80 ° C. and aging for 1 hour, the mixture was cooled and filtered through a 300 mesh stainless steel wire mesh to obtain a core-shell polymer latex. This latex was frozen at −15 ° C., filtered through a glass filter, and then air-dried at 60 ° C. overnight to obtain a core-shell polymer A.
[0115]
A mixture of 2000 g of this core-shell polymer A and 60 g of ethylenebisstearic acid amide [manufactured by Lion Akzo Co., Ltd., “Armowax”] dissolved in 100 ml of dimethylformamide was mixed using a Henschel mixer, and the solvent was removed under reduced pressure. As a result, a core-shell polymer B was obtained.
[0116]
3. Urea derivatives
(C-1): Allantoin [Kawaken Fine Chemical Co., Ltd.]
(C-2): Allantoin dihydroxyaluminum [manufactured by Kawaken Fine Chemicals Co., Ltd., “ALDA”]
(C-3): Form nitrogen 2 mol powder [Mitsui Chemicals, Inc.]
(C-4): Form nitrogen 3 mol powder [Mitsui Chemicals, Inc.]
4). Antioxidant
(D-1): Triethylene glycol bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate]
(D-2): Pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]
5. Nitrogen-containing compounds
(E-1): Melamine
(E-2): Melamine-formaldehyde resin
(E-3): Nylon 6
[Preparation of melamine-formaldehyde resin (e-2)]
Using 1 mol of formaldehyde per 1 mol of melamine, the reaction was carried out in an aqueous solution at pH 8 and a temperature of 70 ° C. to produce a water-soluble initial condensate melamine-formaldehyde resin without causing the reaction system to become cloudy. Next, the reaction system was adjusted to pH 6.5 while stirring, stirring was continued, melamine-formaldehyde resin was precipitated, and crude melamine-formaldehyde resin granules were obtained by drying. This granular material was washed with warm water at 60 ° C. for 30 minutes and filtered, and then the residue was washed with acetone and dried to obtain a purified white melamine-formaldehyde resin.
[0117]
  Example 16, Reference Examples 1-6And Comparative Examples 1-5
  After mixing a core-shell polymer, a urea derivative as an inhibitor, an antioxidant, and a nitrogen-containing compound in a proportion shown in Table 1 with 100 parts by weight of a polyacetal resin, the mixture is melt-mixed by a twin screw extruder to obtain a pellet-shaped composition. Prepared. Using these pellets, a test piece was molded by an injection molding machine, the amount of formaldehyde generated from the test piece was measured, and the Izod impact strength was measured according to ASTM D256.
[0118]
For comparison, an example in which the inhibitor urea derivative was not added was evaluated in the same manner as described above. The results are shown in Tables 1 and 2.
[0119]
[Table 1]

[0120]
[Table 2]

[0121]
As is apparent from the table, the resin compositions of the examples can remarkably suppress the generation of formaldehyde while maintaining the impact resistance at a high level by the combination of the core-shell polymer and the inhibitor as compared with the comparative example.

Claims (12)

  A polyacetal resin composition comprising a polyacetal resin, a core-shell polymer having a soft polymer core and a hard polymer shell, and at least one inhibitor selected from cyclic monoureido, cyclic diureido, and metal salts thereof. .   The polyacetal resin composition according to claim 1, wherein the core-shell polymer is a core-shell polymer substantially free of free anions.   The polyacetal resin composition according to claim 1, wherein the core-shell polymer is a core-shell polymer emulsion-polymerized in the presence of a nonionic surfactant.   The polyacetal resin composition according to claim 1, wherein the core-shell polymer contains a saturated fatty acid bisamide.   The metal constituting the metal salt of cyclic monoureido or cyclic diureide is alkali metal, alkaline earth metal, periodic table group 1B metal, periodic table group 2B metal, periodic table group 3B metal, periodic table group 4B metal, and periodic table 8 The polyacetal resin composition according to claim 1, which is at least one metal selected from the group consisting of group metals.   The polyacetal resin composition according to claim 1, wherein the inhibitor is allantoin or a salt of allantoin and a metal.   The polyacetal resin composition according to claim 1, wherein the inhibitor is allantoin dihydroxyaluminum.   The polyacetal resin composition according to claim 1, comprising 1 to 100 parts by weight of a core-shell polymer and 0.01 to 10 parts by weight of an inhibitor with respect to 100 parts by weight of the polyacetal resin. Further, polyamino triazines, amino tree Abura及 beauty polyacetal resin composition of claim 1 further comprising at least one nitrogen-containing compound selected from a polyamide resin.   A polyacetal resin molded article comprising the polyacetal resin composition according to claim 1.   11. The polyacetal resin molded article according to claim 10, wherein the molded article is at least one selected from automobile parts, electrical / electronic parts, building materials / piping parts, daily / cosmetic parts, and medical parts. (1) When stored in a sealed space at 80 ° C. for 24 hours, the amount of formaldehyde generated is 1.5 μg or less per 1 cm ² of surface area of the molded product, or (2) stored in a sealed space at 60 ° C. and saturated humidity for 3 hours. The polyacetal resin molded product according to claim 11, wherein the amount of formaldehyde generated is 2.5 µg or less per 1 cm ² of surface area of the molded product.